A rail-to-rail high speed comparator with LVDS output in 0.18-μm SiGe BiCMOS Technology

Achieving low propagation delay in comparators under low input overdrive voltage is challenging. To overcome this difficulty, this paper presents a novel rail-to-rail high-speed comparator. By clamping the output node of the current summation circuit relative to a fixed level $V_C$, the overdrive recovery time under large signal is successfully reduced. Moreover,by adopting a cascaded approach with multiple stages of high bandwidth and low gain,not only is the comparator’s gain enhanced,but it also acquires higher bandwidth. Ultimately, the comparator’s output is transmitted at high speed through an LVDS interface. This design is implemented using $0.18\mu m$ SiGe BiCMOS technology. Simulation results show that the comparator has a static power consumption of 26.4 mW, and for 5 mV input overdrive, the average propagation delay is about 1.09 ns.